What kind of torque should it take to turn over a 406 with the plugs removed, but the accessories connected (elec water pump)??????

Mine took almost 65ftlbs to turn over. Seems awfully high to me. My valve springs are only 160 on the seat and around 420 over the top. It's a full roller set up too.

 

That sounds about right. The problem with Small block Chev's is the valve train. If you were to convert to a Jesel type shaft rocker the torque to turn it over would be around 12 pounds of torque.

I read an article on Jesel and he was building a small block and big block at the same time. The shortblocks took 8 and 12 pounds of torque to turn respectively. With the heads and valvetrain installed the torque to turn the SBC was 75 and the BBC was 18. It took him a while to figure out what was happening, after he initially thought he did something wrong. What he found was the two engines have different rocker pivot lengths, which means the fulcrum is not in the same place on the rocker arm. The short SBC rocker doesn't have as much leverage as the BBC rocker. He saw a need, and invented the Jesel shaft rocker which has longer rockers for better leverage, and the added benefit of rolling the roller end over the valve instead of sliding it like most other roller setups do.

 

There is something wrong with this report. I don't know if the article was poorly written or maybe it was misunderstood. Jesel knows that the SBC uses a 1.5:1 rocker ratio and that the BBC has a 1.7:1 rocker ratio. I doubt he newly discovered that. The pivot point, which IS the fulcrum, HAS to move to make it a different ratio. By definition, the rocker arm ratio IS the leverage. Are you saying that Ralph's long block that takes 65 ft lbs of torque to turn over, will will only require 12 ft lbs of torque by substituting a Jesel shaft rocker arm set up? I can't even legitimize that rediculous position by saying I don't believe it. No fricken way!!!

Ralph,
Is that 65 ft lbs, breakaway torque, or the steady force required for rotation?

RACE ON!!!

 

Jim, i guess it's breakaway. I kept turning up the torque wrench until i could turn the engine with clicking the wrench. I dont know how i'd even measure steady force, but the engine just felt stiff, which prompted me to check the torque required to turn it. If i remember correctly, it took about 25-30 ftlbs to turn just the short block on the stand when it was being built.

At least it seems to have stopped creeking.....LOL.

 

Are the cylinders dry of any oil?

 

This was about 2-3 hours after i shut it down. Engine not completely cooled.

 

Yes, that is breakaway torque. The torque required to maintain rotation couldn't be measured with a "click" type of torque wrench. You would need a deflecting beam type of wrench.

RACE ON!!!

 

The article (Chevy High Performance July 2003) states "The pivot length is the length of the rocker from its fulcrum to the tip where it contacts the valve stem. A typical sbc has a rocker arm pivot lenght of 1.4". A bbc employs a pivot length of 1.65". That may not sound like a big deal, but when Dan (Jesel) returned to the shop he built a set of 1.54" pivot length rocker arms for his sbc and the rotating torque dropped from 75-12 ft-lb. The problem is that the sbc rocker not only pushes down on the valve tip, it must also sweep across the valve tip causing incredible friction. In fact, Dan noticed the roller tips were not even rolling-they were being dragged and pushed. Increasing the pivot lenght decreased the rockers sweep. Valvetrain friction from stock pivot length rockers not only cost hp, it causes premature valvestem and guide wear leading to poor valve sealing."

The big decrease in rotational torque is the result of less "sweep" in the rocker resulting in less valve to guide friction. I incorrectly stated the fulcrum point was changed when in fact the length of the rocker was changed. I shouldn't read tech articles at midnight! I should have included more info in my reply but it was late and I didn't want to type the whole article.

 

Was it in gear

Sounds way too much to me, I have a 406 solid roller with 450# springs and I adjust the valves all the time with the spark plugs out and I would say it takes about 20 -30lbs tops

 

I dunno, it runs OK and does not run unusually hot. I'm probably using 100 hp just to turn the engine......LOL.

 

A quote from John Lingenfelters book on SBC's "Perhaps the most misunderstood point is that the roller tip actually rolls across the valve stem tip. This is not true. Even though the roller will spin easily between your fingers, once loaded against valve spring pressure the roller merely slides across the valve stem."

 

I haven't had time to search for that article, either on line or in my library, but I find that claim, hard to swallow. We know that most of the friction is in the piston rings. We also know that the change to the valve train didn't eliminate ALL of the valve train friction, but you would have us believe that the valve train modification resulted in eliminating 84% of all the engine friction??? I was born during the day, but... If you have a link to that article, please post it.

RACE ON!!!